In general, a solar cell module of a thin film type includes a first electrode layer separated by a first isolation groove, a first semiconductor layer, a transparent conductive layer and a second semiconductor layer which are separated by a second isolation groove, and a second electrode layer separated by a third isolation groove. Such a solar cell module is fabricated as described below.
First, the first electrode layer is formed on a substrate having transparency, and thereafter the first isolation groove is formed by partially removing the first electrode layer by use of laser. Next, the first semiconductor layer is formed on the first electrode layer and simultaneously is filled into the first isolation groove. Next, the transparent conductive layer and the second semiconductor layer are sequentially formed on the first semiconductor layer.
Next, the second isolation groove is formed by partially removing the first semiconductor layer, the transparent conductive layer, and the second semiconductor layer by use of laser. Next, the second electrode layer is formed on an inner wall of the second isolation groove and on the second semiconductor layer. Next, the third isolation groove is formed in a position opposite from the first isolation groove across the second isolation groove, by partially removing the first semiconductor layer, the transparent conductive layer, the second semiconductor layer, and the second electrode layer by use of laser.
In such a solar cell module, since the transparent conductive layer contacts the second electrode layer formed on the inner wall of the second isolation groove, a current flowing along the second electrode layer flows into the transparent conductive layer, and therefore a leak current occurs.
In order to prevent the occurrence of the leak current from the second electrode layer to the transparent conductive layer, it is known that a transparent conductive layer isolation groove for separating the transparent conductive layer is formed by partially removing the transparent conductive layer between the first isolation groove and the second isolation groove (see Japanese Patent Application Publication No. 2002-261308, for example).
Here, a voltage potential difference between the first semiconductor layer and the second semiconductor layer is small in a region between the first isolation groove and the second isolation groove. If the width of this region is increased, the amount of the current that can be taken out of the first semiconductor layer and the second semiconductor layer is decreased. It is therefore preferable to form such a region having as small width as possible.
However, if the transparent conductive layer isolation groove is formed between the first isolation groove and the second isolation groove, the width between the first isolation groove and the second isolation groove is increased, as compared to the case where the transparent conductive layer isolation groove is not formed.
Therefore, although the occurrence of the leak current between the second electrode layer and the transparent conductive layer can be prevented by forming the transparent conductive layer isolation groove, there is a problem the amount of the current that can be taken out of the first semiconductor layer and the second semiconductor layer is decreased.
Accordingly, the present invention has been made in view of the foregoing problem and an object of the present invention is to provide a solar cell module capable of preventing occurrence of a leak current between the second electrode layer and the transparent conductive layer without increasing the width of the region having a small voltage potential difference between the first semiconductor layer and the second semiconductor layer.